The incident took place on Sunday when Mujahid and his son Bilal were carrying refined oil from Ghaziabad to Haldwani in Uttarakhand in their truck, Khatauli SHO Sunil Kumar Tyagi said.
Four robbers intercepted the vehicle on Ghaziabad-Haridwar National Highway, killed the duo by slitting their throats, and fled with the truck, police said, adding, the accused threw the bodies on two different roads.
The incident came to light when police found Bilal's body in Muzaffarnagar, Tyagi said.
The four, identified as Naushad, Nazim, Imran, and Mujammil, were arrested and confessed to their crime during interrogation, he said.